Blow molding has been utilized for a number of years to form a variety of hollow plastic parts. It has proven effective to form single layer as well as multi-layer materials and, with more recent advances, has been used to form a variety of complex shapes, for instance via 3D blow molding techniques. The versatility of blow molding processes is providing a route to the formation of multi-functional, one-piece blow molded components that can reduce weight and simplify assembly of consumer goods as well as manufacturing and production devices.
Many of the applications that could benefit from the utilization of blow molded components are quite demanding, and require components that can withstand a variety of both chemical and mechanical insults. For example, components for use in transport and transportation applications should be able to provide a long life under operating conditions that include temperature fluctuations as well as movement during use. Thus, materials generally require both strength and flexibility. Moreover, materials should be resistant to and impermeable to fluids that may be encountered during use such as oil, gas, coolants, water, air, etc. that may also be heated or cooled during use.
Polymeric materials that can be blow molded to form products that exhibit flexibility in addition to high strength and resistance properties are of significant commercial interest. Such materials have been formed in the past by uniformly mixing an elastomeric component with a thermoplastic polyolefin such that the elastomer is intimately and uniformly dispersed as a discrete or co-continuous phase within a continuous phase of the polyolefin. Vulcanization of the composite crosslinks the components and provides improved temperature and chemical resistance to the composition. When vulcanization is carried out during combination of the various polymeric components it is termed dynamic vulcanization.
Polyarylene sulfides are high-performance polymers that may withstand high thermal, chemical, and mechanical stresses and are beneficially utilized in a wide variety of applications. Polyarylene sulfides have often been blended with other polymers to improve characteristics of the product composition. For example, elastomeric impact modifiers have been found beneficial for improvement of the physical properties of thermoplastic compositions. Compositions including blends of polyarylene sulfides with impact modifying polymers have been considered for high performance, high temperature applications.
Unfortunately, elastomeric polymers generally considered useful for impact modification are not compatible with polyarylene sulfides and phase separation has been a problem in forming compositions of the two. Attempts have been made to improve the composition formation, for instance through the utilization of compatibilizers. However, even upon such modifications, compositions including polyarylene sulfides in combination with impact modifying polymers still fail to provide product performance as desired, particularly in applications that require both high heat resistance and high impact resistance.
What are needed in the art are thermoplastic compositions that are amenable to blow molding formation methods and that also exhibit high strength characteristics as well as resistance to degradation, even in extreme environments. More specifically, what are needed are blow molded components that can withstand utilization in harsh working environments.